Plating surgical needles



Dec. 23, 1958 R. M BANKS ETAL 2,365,375

PLATING SURGICAL NEEDLES Filed March 27, 1956 l7 29 F: ;;h 30 28 I 23 27/4 26 /a E- 6\E 5 22 W 20-5 C 25 2/ /9 r I f J INVENTORS- REGINALD MARSHBAN/(S,

BYROBEI? T GHA RL ES BELL,

W M 7mm ATTORNEY.

United States Patent PLATIN G SURGICAL NEEDLES Reginald Marsh Banks,Rye, N. Y., and Robert Charles Bell, Stamford, Conn., assignors toAmerican Cyanamid Company, New York, N. Y., a corporation of MaineApplication March 27, 1956, Serial No. 574,160

3 Claims. (Cl. 128--339) This invention relates to improvements innickel-nickel phosphide plated needles for surgical sutures, the suturedsurgical needle and methods and apparatus for producing them.

At present surgical needles are produced from a fairly high carbon steelso as to give a tough sharp needle point for use in suture work. Many ofthe needles are of the eyeless type in which various means are used forconnecting a single strand of a suture into a needle. Such needledsutures are then stored until time for use. Certain sutures, such as gutsutures, must be stored in conditioning fluid such that the suture is inproper condition for use when removed from the storing container. Othersfor use with silk sutures, or other types of sutures may be stored dry.Under either condition it is necessary that the needles remain brightand shiny and appear free from contamination for esthetic reasons, aswell as practical utility. In many instances the point of the needle isof a much harder metal than the shank or butt end of the needle.

In the past it has frequently been customary to store the needled gutsutures in a conditioning fluid to which a rust inhibitor had beenadded. The use of such a rust inhibitor induces additional problems asit may deleteriously effect the gut or the label which is present toidentify the needled suture. Among other materials sodium nitrite hasbeen used, which is apt to discolor paper.

Obviously, it would be advantageous if a needle were available which didnot require special handling to prevent corrosion. The requirements arevery rigorous because the cracks and crevices present in the flangeportion of the eyeless needle, which are necessary so that the needlemay be clamped around the suture, are such that it is diflicult to cleanthe needle, and there are many corners in which corrosion may beinitiated. It would seem obvious to use a plated needle to preventcorrosion. However, conventional plates such as nickel plate are notsatisfactory because if a plate on the needle is sufiiciently thick toprevent corrosion, the plate tends to become brittle, and flakes offwhen the flange of the needle is closed about the suture. It would thusseem that there are conflicting requirements, which have in the pastpresented insuperable difficulties. t

It is necessary therefore to secure a plate which is smooth, uniform andsufficiently ductile to remain on the needle during subsequentoperations, which is bright and shiny in order to be acceptable, andinsures corrosionresistance. The nickel-nickelphosphide plate issuperior in corrosion-resistance to electrolytic nickel plate.Surprisingly it is found that an electrodeless plate of nickelnickelphosphide is of such characteristics that a suitable plated needle isobtained. It may be that the nickel phosphide in the nickel givessufficient ductility and resilience so that the plate will remain on thesurface of the needle without rupture even during closing operations,and the superior throwing power of an electrodeless plating solutioninsures that the cracks and crevices in the flange of Mice the needleare adequately plated and that the corners and I re-entrant edges areadequately plated before the plate on any portion becomes so thick as tobe brittle. Additionally, the nickel-nickel phosphide plate is thinenough so that sharp points and edges of the needles remain sharp.

Electrodeless plating solutions and processes have been disclosed fromtime to time. One which is particularly advantageous in conjunction withthe present manufacture of surgical needles is that described in aU. S.patent to Brenner, 2,532,283, Nickel Plating by Chemical Reduction. Thecompositions and methods there described when applied to a mass ofsurgical needles gives amazingly satisfactory results. It is desirablethat to insure a smooth and uniform plate over all surfaces of theneedles, that the needles be agitated during the plating operations, andby using an agitating device so that the needles are tumbled. Continuousagitation is convenient but not nec essary. The nickel-nickel phosphidecoating is smoothly and uniformly adherent over the entire surface ofthe needles.

It is preferred that the nickel be furnished by soluble nickel saltssuch that not substantially in excess of four parts by weight to partsby weight of solution of nickel ion is present and the hypophosphiteradicals be present not substantially in excess of three parts by Weightper 100 parts by solution. It is: preferred that the solutions be hotduring use and whereas the nickel of the solutions can be exhaustedduring the plating process, normally the amount of nickel-nickelphosphide required for the plate is so small that it is more convenientto only partly utilize the nickel present in the solution and replacethe solutions, because the plating solutions will not remain stable overan extended period of time.

The needles must be clean prior to plating, and conventional cleaningprocesses may be used, such as either a caustic or alkaline phosphate,or a solvent degreasing, or both followed by acid dip which activatesthe surface of the needles.

It is very diflicult to measure the exact thickness of the coating onthe surface of the needles either directly with a micrometer, orindirectly by area and weight relationships. As nearly as can bedetermined by measurements, a plate which is uniform and from about 0.05to 0.35 thousandth of an inch gives a satisfactory plate which issufficiently thick to be corrosion-resistant, and sufficiently thin tobe ductile enough to permit closing the flange of the needle about thesuture without rupture. The nickel-nickel phosphide coating containsmore than one phase, and on analysis of the plate obtained by prolongedplating, had a phosphorus content of 2.17%, although this may vary withthickness and plating conditions. Some publications report a higherphosphorus content.

The accompanying drawings show:

Figure 1 a curved eyeless needle,

Figure 2 a needled suture,

Figure 3 the plating apparatus.

As shown by Figure 1 conventional eyeless needles have a flange 12 whichconsists of an opened portion of the closing die which gives both abending and a shearing action, which tends to scrape off the plate fromthe flange portion of the needle. The interior portions of the flangeare particularly difficult to plate smoothly and uniformly 1 i and areareas in which corrosion most easily occurs It Patented Dec. 23, 1958-is impractical to attempt to electroplate the flange of a needle so thatthe interior portions are corrosion-protected by the plate, and theexternal portions are not so heavily plated as to become brittle.

As shown in Figure 3 the needles are conveniently plated in a rotatingcontainer. Because surgical needles are rather small and areconveniently plated in fairly small batches, a glass flask is convenientas a plating container. As shown in Figure 3 a conventional Erlenmeyerflask 14 has agitating dents 15 formed in the side near the bottomthereof. For example a 4-liter Erlenmeyer flask may have about a dozendents formed equally spaced around the lower periphery by heating theglass in spots and using the blunt end of a tile to force the glass wallinteriorly of the flask to form a dent. In rotating, these dents pick upthe needles and cause the mass of needles to move with the flask and betumbled rather than sliding around the interior surface of the flask.The number or shape of the dents is not critical.

The flask is supported in a hot Water bath 16. The hot water bath may beof stainless steel. it is preferably provided with a cover 17. The bathwater 18 may be heated by heating means 19, which may either be anelectrical heater or a steam injector to maintain the bath at a desiredtemperature usually near boiling. Inside the hot water bath is a groupof support rollers. A bottom support roller supports the flask axially,and consists of a non-corrosive roller 20 rotatably mounted in a supportbracket 21. The roller is preferably of a non-corrosive material whichis self-lubricating, such as Teflon or Nylon. Such plasticself-lubricating materials do not require lubrication and resist theeffects of the boiling water for long periods. The neck of the flask issupported on neck support rollers 22 which are journaled in the necksupport roller bracket 23. Near the lower part of the periphery of theflask are the rotating rollers 24 which are mounted on shafts 25, whichare in turn rotated by the stirring motor 26 through a gear reducer 27.As so journaled the flask can easily be placed in and removed from thehot water bath with a minimum of effort. Opposite the neck of the flask,when in position on the rollers, is a thermometer support 28, which is atubular bracket, having a hole at the bottom thereof for the insertionof a thermometer. A thermometer 3t? is positioned in the thermometersupport by a stopper 2.9. By inserting the stopper down into theinterior flask the temperature of the plating solution during use isascertained.

Obviously, the apparatus may be modified somewhat from the details shownfor purposes of convenience .depending upon the quantity of material tobe plated in one batch, and the materials which are available forconstruction. The apparatus as shown, using a 4-liter flask, isconvenient for plating a batch of several thousand surgical needles atone time, depending somewhat on the size of the needles being plated.

For small size batches, particularly for experimental or laboratory use,an ordinary 250 milliliter Erlenmeyer flask which is agitated by hand isconveniently used. An external magnet suitably moved may be used toagitate the needles. For plating on a larger commercial scale a glasslined barrel may be used.

As illustrative but not in limitation of the invention the followingexamples are given, in which parts are by weight unless otherwisespecified.

Example 1 100 eyeless needles, designed for a number size suture, arecleaned by washing twice in a mixture'consisting of 40 volumes xylene,40 volumes naphtha, and 20 volumes of methyl ethyl ketone, rinsed inacetone, and dried on' tissue paper. The needles are immersed in ahydrochloric acid solution for one minute, washed,

4.. and immersed in 100 milliliters of a solution consisting of:

Parts Nickel chloride (NiCl -6H O) 10 Sodium hypophosphite (NaH PO -H O)l Ammonium chloride (NH Cl) 5 Sodium citrate (Na C H O- )-l1H O l0Sufficient water to make up to 100 parts.

The pH is adjusted to pH 8 using ammonium hydroxide. The needles areplated for 15 minutes with agitation, then removed from the solution,washed with water, and permitted to dry. A bright plating results whichdoes not crack on sharp bending. The plate on the flange is so adherentthat the flange may be bent until the flange itself breaks before theplate is detached from the needle.

Example 2 The above run is repeated leaving the needles in the solutionfor 30 minutes. The resulting needles show a. bright plate which issufliciently adherent that the flange may be sharply bent withoutcracking, or the needles may be attached to sutures using standardfianging dies Without damage to the plate. The plate has the brightnesscharacteristic of a bright nickel plate, even though the plate itself isa nickel-nickel phosphide.

Example 3 Example 1 is repeated using a plating solution the pH of whichis not adjusted, but which measures between pH 8 and pH 9 during theplating operations. The needles are permitted to remain in the platingsolution for 30 minutes, then removed and washed. On testing thethickness of the plate it is found to be approximately 0.0002 inch.

Example 4 Example 5 100 very small needles, designed for a 6/0 sutureare treated by following the method of Example 4 except that the needlesare plated for minutes. A smooth bright uniform plate results. Theneedles may be attached to gut sutures without the plate on the flangeportion cracking.

Example 6 needles, designed for a 6/0 suture, are washed in 100milliliters of a washing solution consisting of 40 volumes of xylene, 40volumes of ligroin, and 20 volumes of methyl ethyl ketone. The needlesare washed twice, are then rinsed in acetone and dried on paper. Theneedles are immersed in a 2% hydrochloric acid solution for 2 minutes,washed and are then placed in the plating solution containing:

Parts Nickel chlor 20 Sodium hypophosphite l Ammonium chloride 5 Sodiumcitrate 10 Suflicient water to make up 100 parts.

The needles are plated for 20 minutes with a solution at a pH of 8, andthen washed and dried. A. bright good plate is obtained, and whichadheresto the needles during the flanging operation. 7

Example 7 80 medium size, curved eyeless needles are washed twice in 200milliliters of xylene, and then washed with 100 milliliters of acetone.The needles are air-dried and then pickled in 150 milliliters of 5%hydrochloric acid for 30 seconds and washed with water until the wash isneutral to litmus. A plating solution is prepared from:

Grams Nickel chloride 135.5 Sodium hypophosphite 13.5 Ammonium chloride67.9 Sodium citrate 135.3 Water 1000 To this mixture is added 175milliliters of concentrated ammonium hydroxide, thereby giving asolution with a pH of 8.4. 200 milliliters of this plating solution isheated to 80 C. and the needles are added thereto. The needles areagitated for 5 minutes, and then the solution is washed out with runningwater, the needles rinsed with water, and allowed to air-dry. A brightfinish is obtained on the needles. After flanging on the gut sutures,and shaping of the needles no damage to the plate is observable under amicroscope. The needles are corrosion-resistant when allowed to stand inair for a period of at least several months.

Example 8 5000 electropolished needles for a number 3/0 suture areallowed to stand in 500 milliliters of xylol for 20 minutes at roomtemperature. The needles are then rinsed with water and placed into asolution containing 200 milliliters of water, and 113.4 grams of MetexT-103 at 86 C. The needles are allowed to stand for 3 minutes, and thenrinsed. They are then placed in 500 milliliters of a solution containing60 grams of NH HF and 360 grams Troxide per liter for 30 seconds at roomtemperature. Fluorides are particularly useful in conditioningelectropolished needles for plating. The needles are again rinsed withwater, placed in a Metex T-103 cleaning solution at 77 C. for 3 minutes,rinsed, and placed in 2000 milliliters of solution containing 120 gramsof Troxide per liter for 1 minute at 56 C. and then rinsed withdistilled water. Metex T-103 is a sodium hydroxide, sodiummetaphosphate, sodium metasilicate, plus wetting agent cleaner, andTroxide is a sodium bisulfate and Wetting agent pickling agent preparedfor the electroplating industry by MacDermid, Inc. of Waterbury,Connecticut.

In large size batches it is generally more convenient to use alkalinedegreasers in aqueous solutions rather than solvents because of the firehazard of using inflammable solvents. The needles may alternatively becleaned by using a wash composed of 40 volumes of xylene, 40

volumes of ligroin, and 20 volumes of methyl ethyl ketone, and afterwashing the needles twice, rinsing with acetone, then air-drying ontissue paper.

After being cleaned 5000 needles are placed in 2500 milliliters of aplating solution, prepared as in Example 7, for 10 minutes at 81 C. inthe apparatus described above and shown in the drawings. The needles arewashed in distilled water, then air-dried. The needles then have abright finish which does not flake, or peel when the needles are flangedon the gut and shaped. The needles are corrosion-resistant, and may beleft exposed to air for periods of some several months withoutexhibiting corrosion or darkening of the plate. The needles areresistant to the normal conditioning fluids which may be used in storingof surgical gut sutures. A corrosion-inhibitor is not required. Theneedles may be sterilized by heat, wet or dry, or given otherconditioning treatment for the suture without damage or corrosion to theneedles.

Example 9 50 eyeless needles are placed in a 250 milliliter Erlenmeyerflask in which they are kept for the entire plating process. The needlesare washed twice with xylene, then with acetone. The acetone is pouredoff, and 5% aqueous hydrochloric acid is added. The needles are pickledfor one minute, the acid poured off, and the needles are Washed withWater. The water is drained off and 100 milliliters of cold platingsolution is immediately added. The plating solution contains:

Percent Nickel chloride 10 Sodium hypophosphite 1 Ammonium chloride 5Sodium citrate 10 Water 74 Ammonium hydroxide-sufficient to adjust pH to8.

The flask is heated in a steam bath to C., and the plating time measuredfrom the time at which the temperature reaches 80 C. After plating for 8minutes, the plating solution is poured oil, and the needles are washedwith water, then with acetone, and air-dried.

The plate is adherent, corrosion-resistant, and sufficiently ductile topermit attaching to sutures.

Example 10 Example 9 is repeated, the plating time being 15 minutes.

Corrosion-resistant needles with a ductile plate are obtained. 1

We claim:

1. A needled surgical suture comprising: an eyeless needle, a shiny,corrosion-resistant, flexible nickel-nickel phosphide plate on thesurface thereof, and a flexible surgical suture swaged to said needle.

2. A needle for a surgical suture comprising: an eyeless needle, and onthe surface thereof, a shiny, corrosionresistant, flexible nickel-nickelphosphide plate.

3. A process for preparing shiny, corrosion-resistant nickel-nickelphosphide plated needled surgical sutures which comprises: cleaningsteel eyeless needles, immersing in an aqueous solution of a nickel saltand an alkaline hypophosphite, the nickel ion being present in an amountnot substantially in excess of about 4 parts by weight to about parts byweight of said solution, the hypophosphite radical being present in anamount not substantially in excess of about 3 parts by weight to about100 parts by weight of said solution, plating said needles byautocatalytic reaction of said nickel salt and said hypophosphite, at atemperature between about 70 C. and 100 C., until a ductilecorrosion-resistant nickel-nickel phosphide plate is obtained, washingand drying the needles, and swaging said needles onto suture strands.

References Cited in the file of this patent UNITED STATES PATENTS145,217 Leiter Dec. 2, 1873 230,857 Briggs Aug. 10, 1880 1,960,117Lydeard May 22, 1934 2,532,283 Brenner Dec. 5, 1950 2,620,028 Kohut Dec.2, 1952 2,694,019 Gutzeit Nov. 9, 1954 2,816,846 Talrney Dec. 17, 1957

1. A NEEDLED SURGICAL SUTURE COMPRISING: AN EYELESS NEEDLE, A SHINY,CORROSION-RESISTANT, FLEXIBLE NICKEL-NICKEL PHOSPHIDE PLATE ON THESURFACE THEREOF, AND A FLEXIBLE SURGICAL SUTURE SWAGED TO SAID NEEDLE.